Embryology Intro Sept27 M1 Flashcards
Menstruation: how long occured before fertilization
2 weeks
2 ages that can be given prenatally and difference
Fertilization age
Last menstruation period age (2 weeks more)
two developmental phases prenatally + length + total length
embryonic: 60 days (2 months, 8 weeks)
fetal: 206 days (7 months, 30 weeks)
Total: 266 days (9 months, 38 weeks)
most important prenatal phase of development and why (3)
embryonic.
Most important events.
Great impact on subsequent dev
Most malformations there (most vulnerable phase)
T-F: time of birth is fixed
Range that can go from 230 to 290 days of gestation
gestation definition
developmental phase between fertilization and birth (prenatal)
ways to estimate date of birth (2)
add 266 days to estimated day of fertilization
add 280 days to last normal menstruation period (LNMP)
embryonic development description + 2 events that summarize that
formation of cells, tissues and organs (with cellular interactions between cells)
Histogenesis
Organogenesis
Histogenesis def
Org of cells into tissues
Organogenesis
Interactions between tissues to form organs (Ex. epith + CT + vascular and nerves form liver)
which embryonic event is the most vulnerable and why
organogenesis bc very complex
how embryonic dev forms lots of lineages
Embryogenesis involves prolif of cells and tissues that differentiate infunction (muscles, epith, etc.)
Fetal development description
transitional phase, active differentiation and formation of organs and systems continues to prepare maturation and birth
Postnatal development phases (6)
Neonate, Infant, child, puberty, adolescence, adult
ontogeny definition
study of continuous changes from fertilization to death
most vulnerable postnatal phase and why
neonate. bc exposed to new enviornment outside uterus
neonate def
birth to 1 month old (new born)
infant def
1st year of postnatal development (birth to 1 year old)
child def
1 year old to puberty
puberty def
female first menstrual cycle and male production of mature spermatozoa
adolescence def
physical and sexual maturation of secondary sexual characteristics giving ability to reproduce
adult def
full growth of long bones and maturity
what is visible (developped) in 40 days embryo
brain, eye, nervous system, lung, heart, liver, umbilical cord, upper limbs + fingers, lower limbs wo fingers
why most serious congenital malformations occur during embryonic phase of dev
vulnerable bc so many processes happening and complex
5 mechanisms of development
1) cell division, mitosis
2) cell migration
3) cell to cell interaction
4) programmed cell death (apoptosis)
5) Genetically controlled transitions between cell types (EMT MET)
Most vulnerable mechanism during development and why
Mitoses bc are affected by radiation and other things
hypoplasia and hyperplasia in dev, def
abnormal reduced or increased number of cell divisions
conequence of a mass being under or overdeveloped other than it working differently
affects neighboring organs and their placement
Pierre Robin sequence (3)
1) Mandibular micrognathia: prevents descending of tongue causing cleft palate (CF)
2) CF: wider and U shaped rather than regular CP
3) Glossoptosis: causing airway obstruction
Pierre Robin sequence reason for it (what happened)
hypoplasia causes mandibule to be small, prevents tongue from going down and palate from closing
cell migration: what cells do long range migration (3)
Primordial germ cells (PGCs), Neural crest cells (NCCs), Hematopoietic stem cells (HSCs)
cell migration: what cell do short range migration
cells within tissues and organs
tissue migration def and how controlled
convergent-extension of tissues regulted by planar-cell polarity genes
(genetically regulated)
Cell-to-cell interaction characteristics (3)
direct contact, short distances, matrix
What cells form the head and neck and how much do they migrate
Neural crest cells (NCCs)
Long range migration
Cell interaction first step and its consequence
Form junction (direct cell contact) and this affects the genetics
what molecules can influence cell interaction
signaling molecules in the matrix and receptors on cell surfaces
what does binding of a signaling molecule to a cell’s receptor tell the cell
tells it to migrate towards a certain direction, to a certain cell
what happens when two cell receptors interact (cells form direct contact) and consequence on cell that just arrived
new patterns of gene expression. cell now transformed, becomes different, can secrete new substances in matrix to create gradient effect
Gradient effect of molecules in matrix: what’s the importance
influences differentiation
How matrix regulates the molecules present in it
Regulates ligand availability. Ligands can become active
Feedback mechanism in cell-to-cell interaction
cell with new gene expression can send molecule back to initial cell (paracrine) to control gene expression of initial cell
Programmed cell death (Apoptosis) function
ensures critical cell numbers and sculpturing of organs
programmed cell death: in what phases of development?
prenatal and postnatal
apoptosis function in postnatal development
maintain optimal cell number in renewing tissues. Balance mitosis and cell death
How programmed cell death discovered
with syndatylyl: unseparated fingers at birth
Genetically controlled cell type transitions: 2 exemples
Epithelial-mesenchyme transition EMT or opposite (MET)
Epithelium definition (4)
cells polarized, lining cavities, BM, junctional complexes
EMT steps (5)
1) loss of polarity
2) cytoskel reorg
3) BM broken down
4) Cell passes through BM
5) Cell changes shape
what controls EMT and MET
genetics
3 phases of prenatal dev and what days
Pre-implantation phase (days 1-6)
Implantation phase (days 6-10)
Post-implantation phase (implantation to birth)
Pre-implantation phase def
Fertilization to implantation. Dev in Fallopian tube to form blastocyst (independent dev in zona pellucida)
Implantation phase def
active embedding and erosion in endometrium + establishement of early placenta (dependence on mother’s blood for nutrition)
Post-implantation phase def (or significance)
dependence on mother’s blood for nutrition, excretion and gaseous exchange
where fertilization occurs in fallopian tube
near ovaries
blastocyst vs zona pellucida (and function of zona pellucida)
blastocyst: result of cell divisions of zygote
zona pellucida: protein shell around it (important role in indep development of zygote)
Why IVF success rate is low
When fertilization, many zygotes get lot of chromosome abnormalities. After first or second division, lot of cell death.
how zygote moves in fallopian tube
cilia in tube + SM contraction
Ectopic pregnancy: why it occurs
when scarring or genetic defects in uterus, not allowed to move there.
secondary oocyte (before fertilization): nucleus, cytoplasm and surrounding
haploid nucleus, cytoplasm rich in RNA and mt, peri-vitelline space surrounds, then zona pellucida
after fertilization, zygote formation and first mitosis, what’s the result
two blastomeres phase
totipotent potential
2nd mitosis result
four plastomere phase
totipotent potential
3rd and 4th mitosis result
8-16 blastomere phase (Morula)
totipotency reduced
how can get twins
if two totipotent blastomeres of the 1st mitosis separate
phase that follows Morula phase and two regions
compaction phase
outer and inner microenvironment
compaction phase: what surface blastomeres do
Develop gap junctions and tight junctions (E cadherins), have polarized apical surfaces, BM forms
what happens after compaction phase (what outer and inner cells do + name of the whole thing)
outer cells become trophoblast (or trophectoderm) and form placenta
inner cells: embryo
outer + inner cells: conceptus
what is cavity between inner cell mass and outer cell mass in conceptus
fluid filled blastocoele
other way to get twins
if inner cell mass separates at the conceptus step
what inner cell mass does at conceptus step (2)
1) Forms a central space within itself: amniotic cavity
2) Forms an endoderm that will line the blastocoele
result when primitive endoderm of inner cell mass proliferates on the trophectoderm
blastocoele lined by primitive endoderm called the yolk sac
Name of two cell types in the embryo when have amniotic cavity and yolk sac
primitive ectoderm (lines amniotic cavity) primitive endoderm (lines yolk sac)
other name for primitive ectoderm lining the amniotic cavity
amniotic epithelium
when done having primitive ecto and endoderm (and yolk sac and amniotic cavity), what happens
primitive ectoderm gives rise to extra-embryonic mesenchyme
extra-embryonic mesenchyme: what it does and what it contains
distributes on (around) yolk sac and amnion contains PSCs (primordial stem cells) and hemangioblasts
hemangioblasts def
multipotent precursor cells that can differentiate into both hematopoietic and endothelial cells.
why we say that the embryo is bilaminar
because has two germ layers (primitive ectoderm and primitive endoderm)
other name for ptimitive endoderm
hypoblast
trophectoderm histology and function
epithelium programmed to interact with uterine endometrium to promote adhesion and invasion
inner cell mass (ICM) function
capable of producing all the cell lineages of the embryo and produces a primitive endoderm
primitive endoderm role
role in subsequent dev of embryo
ICM content
pluripotent cells, embryonic stem cells capable of self-renewal and differentiation
Gastrulation def
formation of the three germ layers (ectoderm, mesoderm and endoderm) that will interact and form all the tissues in the body
